Sister Hong's brainwashing session began when her Bible class ended. Five peasant women had led the Catholic nun to a house in a distant village in Henan province two years ago so that she could teach the life of Jesus. Suddenly, the women vanished and a man entered. For the next five days he refused to let her leave and forced her to debate the Bible. He said the day of judgment is nigh. Jesus has returned. China—the Great Red Dragon from the Book of Revelations—faces destruction. By the end, "I was dizzy. I was confused. He knew the Bible so well," says Sister Hong. Her pleading, plus promises to return, finally won her release. Lightning had struck again.

A fast-spreading sect named Lightning from the East is alarming Christian communities across China by winning large numbers of converts to its unorthodox tenets, often by abducting potential believers. Its followers, who say they number 300,000 but whom observers measure in the tens of thousands, believe that Jesus has returned as a plain-looking, 30-year-old Chinese woman who lives in hiding and has never been photographed. They credit her with composing a third testament to the Bible, writing enough hymns to fill 10 CDs and teaching that Christians who join her will ascend to heaven in the coming apocalypse. They see signs of doom everywhere, from the perfidy of Communist Party propaganda to anthrax spores in the U.S. postal system. According to one of the group's Chinese leaders who uses the alias "Peter" and moved to New York City last year, "The judgment is ongoing in China and will expand through the world."

The sect—which calls itself "the congregation"—operates deep underground. A two-year police campaign against it and other so-called "evil cults," such as Falun Gong, has put 2,000 of its followers in jail, say its spokesmen. Yet by targeting Christian believers it is flourishing—even though its belief that the female Jesus has updated the Bible for China violates core Christian tenets. The appeal seems to be the group's claim to have improved the Christian faith by putting the end of the world into a Chinese context and offering believers a path to immediate salvation. Official Christian churches, by contrast, downplay the Final Judgment, emphasizing instead codes of behavior. That, plus the sect's insistence that China is "disintegrating from within," appeals to peasants, many of whom are poorly grounded in Christian principles and are angry at a government that has failed to raise their incomes or curb corruption.

Fearful for their believers' souls and welfare, leaders of China's roughly 60 million Christians have mobilized. Last year a man claiming to be Lightning's coordinator for north China met secretly with a senior aide to a Catholic bishop in Hebei province to try to convert the Catholic leadership there. He failed, and the bishopric has warned clergies to remain vigilant against Lightning. In Henan, the main church in Dengfeng county called a meeting of 70 lay leaders for a two-day training session on Lightning's "heresies"—but since then five of the leaders have joined the sect. Lightning "is the greatest danger we face today," says a minister named Li who no longer allows strangers to worship in his church in Zhengzhou city, where the sect began a decade ago.

Lightning is the most aggressive Christian sect to emerge in China since the revolution, but it follows a beaten path. In the decades before the communists swept to power in 1949, a Chinese missionary known as Watchman Nee built his congregation, the Little Flock, to 300,000 followers in central China. The sect's emphasis on decentralized congregations launched a home-church movement that helped Christianity survive communist repression. Yet as Little Flock congregations became isolated, they splintered into separate groups. The Shouters, for instance, rewrote the Lord's Prayer to read simply, "Oh, Lord Jesus," and taught followers to holler the phrase while stamping their feet in unison. Other offshoots, like the Disciples, believe that the devil exists in all people—and can be beaten out of them.